Ignition apparatus



4C. H. DAY/KS, JF?.

IGNITION APPARATUS FiledApil 21, 1932 Aam @wa/M adam@ @j/W.

Patented Oct. 1, 1935 UNITED STATES PATENT OFFIQE IGNITION APPARATUS Application April 21, 1932, Serial No. 606,662

5 Claims.

'Ihis invention relates to ignition timers for internal combustion engines and one of its objects is to provide improved means for adjustably securing the timer cam to its driving shaft in such a way as to substantially resist a force which would tend to displace the cam angularly from said shaft. In the disclosed embodiment of this invention the object is accomplished by providing a one-way clutch connection between the cam shaft and the cam supported thereby said clutch being so arranged that it will transmit the driving force of the shaft to the cam in the direction in which the cam is to be driven. The oneeway clutch provides means for adjusting the cam angularly with respect to the shaft. The cam is secured in the adjusted position by a clamping device which causes resilient fingers provided by the shaft to be forced into binding engagement with the interior wall of the hole of the cam through which the camI shaft extends.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing, wherein a preferred embodiment of one form of the present invention is clearly shown.

In the drawing:

Fig. 1 is a fragmentary view, partly in longitudinal section, of an ignition timer provided with a form of the present invention.

Fig. 2 is a fragmentary View looking in the direction of the arrow 2 of Fig. 1, the distributor rotor driven by the timer cam having been removed.

Fig. 3 is a sectional view on the line 3--3 of Fig. 5.

Fig. 4 is a sectional View on a line at right angles to the plane of the section of Fig. 5, and is a View on the section line 4--4 of Fig. 3 or ll--ll of Fig. 5.

Fig. 5 is a sectional view of the'cam and clutch assembly on the same plane as its parts are shown in Fig. l.

Fig. 6 is a side View of the assembly of the shaft and ball bearing.

In the drawing 2D designates a base supporting a timer housing 2| containing a plate 22 upon which is supported a circuit interrupter 23 operated by a cam 24 whose central bore receives a cam shaft 25 journaled upon a ball bearing 26 received by a cup-shaped portion 2l of the bottom wall 2 la of the housing 2 I. The inner race 29 of the bearing 26 is retained upon a shoulder 28 of shaft 25 by a spacer 30 retained by a (Cl. 'f4-568) C-washer 3l engaging a groove 32 provided by the shaft 25.

The shaft 25 is provided at its upper end with four resilient spaced fingers 35 formed by sawing at 35 in Figs. 2 and 6 the tubular upper end of 5 the shaft 25 which had previously been provided with an internal tapered wall thus providing each finger 35 with an internal tapered surface 3l (see Fig. 4). The surfaces 3l of the fingers are engageable with a frusto-conical wedge Sii loosely surrounding a screw 39 and retained thereon by having a portion 40 of the wedge forced loosely into a groove 4l provided by the screw 39. The screw 39 is received by a tapped central hole 42 in the shaft 25. The wedge is provided with diametrically oppositely extending lugs 45 received by diametrically opposite notches l5 provided by the cam 25 in order to provide a splined connection between the wedge 38 and the cam 24. The tightening of the screw 69 20 causes the. wedge 38 to press the ngers 35 against the internal surface of the central bore of the cam 24 thereby binding the cam 25 to the shaft 25 by force due to the binding friction between the internal surface of the wall of the 25 cam 24 and the external surfaces of the fingers and due to binding friction between the internal conical surface of the lingers 35 and the external conical surface of the wedge 38.

The present invention provides a means additional to the wedge 33 and fingers 35 for transmitting motion from the shaft 25 to the cam 2li. This additional means is a one-way clutch connection between the shaft 25 and cam 25 which provides for adjusting the cam 25 relative to the shaft 25 while the screw 39 is loosened. This one-way clutch comprises an inner member 55 attached to the shaft 25 by a key 5i and provided with four notches 52 each notch being dened in part by cam surface 53 which is nonconcentric with respect to the axis of the shaft 25 and which extends from a point a nearest to the shaft 25 to a point b more distant from the shaft 25. Each notch 52 receives a roller 54 urged by a spring 55 in a direction tending to urge the roller between the cam surface 53 and a cylindrical surface 56 provided internally of the cam 2li. Each spring 55 is received within a hole provided by an arm 5l of the member 50. This one-way clutch is so constructed and 50 arranged that it will transmit motion from the shaft 25 to the cam 24 in the direction of rotation of the cam 24 when operating the interrupter 23, but will permit rotating the cam 24 in the opposite direction when the screw 39 is 55 loosened in order to provide for adjusting the cam 24 relative to the shaft 25.

The cam 24 supports and drives a distributor rotor 60 which cooperates with a distributor head 6| in the usual well known manner. Especially when the masses of the cam 24 and of the rotor 60 are relatively great, the torque placed upon the shaft 25 due to sudden acceleration of the shaft will be relatively great. Since the lever arm of this torque or turning moment between the shaft 25 and the cam 24 is relatively small, the turning force will be relatively great. Since the one-way clutch provides for the transmission of the turning force between the shaft 25 and cam 24 at a distance substantially greater than the distances from the axis of the shaft 25 to the internal and external surfaces of the fingers 35, it is apparent that the major portion of the turning force between the shaft 25 and the cam 24 will be taken up through the oneway clutch, thereby relieving wedge 38 and fingers 35 of abnormal strains due to sudden acceleration of the shaft 25.

The inner member 50 of the clutch is retained within the outer member provided by the cam 24 through the agency of a washer 59 attached at 59a to the cam 24. The member 50 is made so that it can be reversed thereby providing an adjustment for the other direction of rotation of the cam to operate the interrupter.

It has been found that cam slippage always occurs when accelerating the engine. That is, the cam tends to remain stationary while its drive shaft tends to move ahead thereby retarding the timing of the ignition. The one-way clutch makes it impossible for the cam to be turned `opposite to the normal direction of ro-tation of the shaft. When the expansible screw 39 is loosened the timing can be adjusted by turning the cam relative to the shaft 25 in the direction of shaft rotation. For example if the timing is 10 degrees late the cam should be rotated 10 degrees ahead. If the timing is 10 degrees early the cam should be rotated ahead (360-10) degrees or 350 degrees which is the same as retarding the timing 10 degrees. After the timing is adjusted the screw 39 is tightened to lock the cam from turning in either direction.

While the form of embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows.

1. In a periodic circuit breaker the combination of a drive shaft having an end portion shaped so as to provide spaced, resilient fingers, a cam mounted upon said fingers, a wedge adapted to be moved axially and shaped so as to wedge the fingers against the interior wall defining a hole in the cam, a screw passing through the wedge and -threadedly engaging the shaft, and a one-way clutch independent of said fingerancl-wedge securing means transmitting motion from the shaft to the cam.

2. In a periodic circuit breaker the combination of a drive shaft having an end portion shaped so as to provide spaced, resilient fingers, a cani mounted upon said fingers, a wedge adapted to be moved axially and shaped so as to wedge i the fingers against the interior wall defining a hole in the cam, a screw passing through the wedge and threadedly engaging the shaft, and a one-way roller-wedge clutch comprising an internal member connected to said shaft and the l interior wall of the cam transmitting motion from the shaft to the cam.

3. In a periodic circuit breaker the combination of a drive shaft having an end portion shaped so as to provide spaced, resilient fingers, a cam mounted upon said fingers, a wedge having a spline connection with said shaft and adapted to be moved axially and shaped so as to wedge the fingers against the interior wall defining a hole in the cam, a screw passing 'l5 through the wedge and threadedly engaging the shaft, and a one-way ciutch independent of said nger-and-wedge securing means transmitting motion from the shaft to the cam.

4. In a periodic circuit breaker the combination of a drive shaft` having an endportion shaped so as to provide spaced, resilient lingers,

a cam mounted upon said fingers, a wedge having a spline connection with said shaft and adapted to be moved axially and shaped so as to wedge the fingers against the interior wall defining a hole in the cam, a screw passing through the wedge and threadly engaging the shaft, and a one-way roller wedge clutch comprising an internal member connected to said 40 shaft and an external shell including a part of the cam transmitting motion from the shaft to the cam.

5. In a periodic circuit breaker the combination of a drive shaft having an end portion shaped so as to provide spaced, resilient fingers,

a cam mounted upon said fingers, a wedge having a spline connection with said shaft and adapted to be moved axially and shaped so as to wedge the fingers against lthe interior wall defining a hole in the cam, a screw passing through the wedge and threadedly engaging the shaft, and a one-way roller wedge clutch comprising an internal member attached to that portion of the shaft into which said screw is threaded and comprising an external shell carried by said cam transmitting motion from the shaft to the cam.

JOHN T. FITZSIMMONS, Administrator of the Estate of Charles H. Davis,

Jr., Deceased. 

